Lance, You're absolutely right that this is a crippling limitation. I argued this point with some vigor a long time ago but with zero luck. What I would have liked to see is:
1) configurable ObjectRendererd, and 2) the ability to have per-category ObjectRenderers This would allow us to log a Foo object differently in different context, the way you ask for. Anders Lance Larsen wrote: > I have looked through the dev list to see if this has come up, but I > haven't seen anything so far. I have been using log4j on a few projects, > and like the configurability and extensibility it provides - very nice - > thankyou for the excellent tool. > > However, there seems to be one part of the architecture where I have run > into limitations, and would like to submit a feature request. Log4j > provides a mechanism to register 'ObjectRenderer(s)' in the > configuration. This is very handy since it allows you to log various > types of objects that log4j would not natively understand by simply > creating a new 'ObjectRenderer' class and including this in the log4j > configuration (no other changes). This part is very nice. The problem I > have run into is cases where I would like the set of 'ObjectRenderer(s)' > to be different for various 'Layout(s)' used at the same time. There > does not appear to be a way to do this. > > The current assumption seems to be that there is one application global > fundamental 'String' mapping for each loggable object type. There seem > to be many cases where you may want to object to be rendered differently > in different contexts. Log4j gives you this flexibility in the > relationship of 'Appender(s)' to 'Layout(s)', but for some reason did > not extend this to the relationship between 'Layout(s)' and > 'ObjectRenderer(s)'. > > One case where having different object renderers is useful is in a case > where there are several things you can pull out of an object. One > 'Appender' (or more correctly 'Formatter') may log part of the info and > another 'Appender' may log different info from the same object. In > another case, two 'Layout(s)' may need the same info, but the string > format may need to be different for each. I do not see a clean way to > currently handle either of these cases. > > My suggestion would be to add a new concept of 'ObjectRendererBundle(s)' > which includes a set of 'ObjectRenderer(s)' that a 'Layout' will use. In > the configuration, the 'Layout' can be assigned an > 'ObjectRendererBundle' in a similar way that an 'Appender' is assigned a > 'Layout'. The 'Layout' class could include a couple of new methods > something like 'setObjectRendererBundle' and 'getObjectRendererBundle' > to access the set of object renders for the 'Layout'. There would > probably be a default 'ObjectRendererBundle' that was global as in the > current case, but the 'ObjectRenderer' model would be more extensible. > > Are there any other thoughts or somments on this? Does this seem like a > reasonable approach? Is this something that you are interested in > including into 'log4j'? > > -Lance Larsen > > -- To unsubscribe, e-mail: <mailto:[EMAIL PROTECTED]> For additional commands, e-mail: <mailto:[EMAIL PROTECTED]>
